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From:   "Wu, Hao" <hao.wu@intel.com>
To:     "Xu, Yilun" <yilun.xu@intel.com>,
        "mdf@kernel.org" <mdf@kernel.org>,
        "linux-fpga@vger.kernel.org" <linux-fpga@vger.kernel.org>,
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        "trix@redhat.com" <trix@redhat.com>,
        "lgoncalv@redhat.com" <lgoncalv@redhat.com>
Subject: RE: [PATCH v5 2/2] Documentation: fpga: dfl: Add description for DFL
 UIO support
Thread-Topic: [PATCH v5 2/2] Documentation: fpga: dfl: Add description for DFL
 UIO support
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Date:   Mon, 4 Jan 2021 04:24:05 +0000
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> Subject: [PATCH v5 2/2] Documentation: fpga: dfl: Add description for DFL
> UIO support
>=20
> This patch adds description for UIO support for dfl devices on DFL
> bus.
>=20
> Signed-off-by: Xu Yilun <yilun.xu@intel.com>
> ---
> v2: no doc in v1, add it for v2.
> v3: some documentation fixes.
> v4: documentation change since the driver matching is changed.
> v5: no change.
> ---
>  Documentation/fpga/dfl.rst | 24 ++++++++++++++++++++++++
>  1 file changed, 24 insertions(+)
>=20
> diff --git a/Documentation/fpga/dfl.rst b/Documentation/fpga/dfl.rst
> index 0404fe6..b8497f3 100644
> --- a/Documentation/fpga/dfl.rst
> +++ b/Documentation/fpga/dfl.rst
> @@ -7,6 +7,7 @@ Authors:
>  - Enno Luebbers <enno.luebbers@intel.com>
>  - Xiao Guangrong <guangrong.xiao@linux.intel.com>
>  - Wu Hao <hao.wu@intel.com>
> +- Xu Yilun <yilun.xu@intel.com>
>=20
>  The Device Feature List (DFL) FPGA framework (and drivers according to
>  this framework) hides the very details of low layer hardwares and provid=
es
> @@ -502,6 +503,29 @@ FME Partial Reconfiguration Sub Feature driver (see
> drivers/fpga/dfl-fme-pr.c)
>  could be a reference.
>=20
>=20
> +UIO support for DFL devices
> +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D

I think the main purpose is to support userspace driver for DFL devices, an=
d
UIO is the option for now. Do you think if the title could be userspace dri=
ver
support for DFL devices?=20

Hao

> +The purpose of an FPGA is to be reprogrammed with newly developed
> hardware
> +components. New hardware can instantiate a new private feature in the
> DFL, and
> +then get a DFL device in their system. In some cases users may need a
> userspace
> +driver for the DFL device:
> +
> +* Users may need to run some diagnostic test for their hardwares.
> +* Users may prototype the kernel driver in user space.
> +* Some hardware is designed for specific purposes and does not fit into =
one
> of
> +  the standard kernel subsystems.
> +
> +This requires the direct access to the MMIO space and interrupt handling=
 in
> +userspace. The dfl-uio-pdev module exposes the UIO device interfaces for
> this
> +purpose. It adds the uio_pdrv_genirq platform device with the resources =
of
> +the DFL feature, and lets the generic UIO platform device driver provide=
 UIO
> +support to userspace.
> +
> +FPGA_DFL_UIO_PDEV should be selected to enable the dfl-uio-pdev module
> driver.
> +To support a new DFL feature been directly accessed via UIO, its feature=
 id
> +should be added to the driver's id_table.
> +
> +
>  Open discussion
>  =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
>  FME driver exports one ioctl (DFL_FPGA_FME_PORT_PR) for partial
> reconfiguration
> --
> 2.7.4